Twisting red leaves, drying cracker green on the stem?!?

[lilblueeyes]

Hello AFN,

We'll after some serious life issues I'm back. I've lost everything I've worked so hard on. All my auto Durban poison, auto aurora indica, dp x ai all gone. But moving forward I've started a new project and hoping for the best.

I bought the Dutch passion 5 pack deal a few months ago. Included were 5 fem of the following. Ultra sour, dark star, sage and sour, mk ultra and sage. Along with that I bought some Magnum autos from buddah. I planted the dark star and ultra sour (photos) on May 8/14 and the magnum autos May 23/14. All planted in Promix potting mix. Why I'm writing is I have an issue I've never ran into.

The dark star and ultra sour were growing fine no problems whatsoever. Healthy happy and growing rapidly. Magnums started off quick but show signs of something wrong. Fast forward to now things are not good at all.

The large fan leaves started rolling/curling in. Brownish red spots start at the tips and work inward. Now the are dry and ready to fall off. They've all been getting tap water boiled and cooled. The dark star and ultra sour just got a watering of 1tbs molasses and a tsp of Epsom salts. About a week ago.

Grow specs:
light: 250w compact floro
soil: Promix potted soil
water: tap, boiled
nutrients: tbsp molasses tsp epsom
Temp: 25 Celsius day/ 20 night. Fan 24/7

I'm at a loss as I've been soooooo lucky this far to not have had any serious issues that were easily fixed, any help is welcome!!

First are the photos, my soil and light and magnum.

 

[Muddy]

Which Pro Mix are you using? I don't recognize that bag and can't see the name on the picture. My experience with Pro Mix is that it's pH is right around 7 right out of the bag, which is a bit high so requires something like aluminum sulfate to lower the initial pH, or feeds at a lower pH to help balance it out. If you have the Pro Mix BX or HP, they don't contain any nutrients so it's up to you to feed everything that the plant needs. That means giving them a mild nutrient solution right from the start. Molasses and epson salts alone aren't enough. What I'm seeing could either be nutrient lockout from the pH being off or a lack of nutrients. What is the pH of your feed water and the pH of your run off?